A villain from the original series of Doctor Who was nearly revived for the most recent series of the BBC Sci Fi starring Matt Smith and Karen Gillan. Writer Gareth Roberts, speaking to the Doctor Who Magazine, revealed that while writing the episode The Lodger the first draft of the script included an original series monster - Meglos! The Cactus villain appeared in the 1980 Tom Baker story Meglos with Baker playing the dual role of the Time Lord and the villainous shape-shifting villain - the story isn't exactly highly regarded though.
"I'd been joking about 'Meglos 2' for years but when I sat down to write the first draft of 'The Lodger' it suddenly seemed right." The writer also revealed that: "Meglos survived in my script for quite a long while—but then we saw the Vinvocci in 'The End of Time,' and as the rest of the story was more comedic, we decided the 'villain' had to be as scary as possible." - Gareth Roberts talking to the Doctor Who Magazine
In the end though Meglos was cut from the story but the series did bring back the Silurians from the original series and the two-part finale saw the return of the Daleks, Sontarans, Autons and Cybermen (along with countless other species in cameo appearances). As the next season of Doctor Who gears who production speculation will doubtless begin as to whom the producers may bring back - the Ice Warriors and Yeti's are current fan favourites tipped for a revival.